System and method for decomposing reclaiming and refusing waste carpet materials

ABSTRACT

A system and method for reclaiming backing material from waste carpet or other products includes a chopper capable of handling large pieces of waste carpet, at least two grinding or granulation steps to reduce the size of the waste carpet pieces and to dislodge carpet fibers from the remaining material, and at least three separation steps to remove the dislodged fibers; one of the separation steps involves vibratory screening. Backing material reclaimed in this manner has a relatively low contamination level, and is suitable for reuse as carpet backing with little need for the addition of virgin backing material. The system and method further provide for the extrusion of the reclaimed backing material for use as new carpet backing.

The invention relates to a system and method whereby floor coveringmaterials are decomposed into fibrous material and granular backingmaterial for recycling purposes, and more particularly to a system andmethod capable of taking used carpet pieces, carpeted floor tiles, orsimilar products, separating them into their constituent materials,including a fibrous material and thermoplastic substrate or backingmaterial, and passing the reclaimed materials to a recycling operationfor reuse.

BACKGROUND OF THE INVENTION

In this era of increased environmental awareness, it is becoming lessacceptable to simply discard used or spent materials of any kind. TheUnited States alone generates many millions of tons of unrecycled trashevery year. Although it is recognized that some materials are notfeasibly reclaimable (such as food, medical supplies, and certain metalsand plastics), an increasing number of materials are reusable aftertreating the material and reforming the material into new items.

Because of this, there is an increasing level of pressure to keep asmuch material as possible out of landfills. Many safely situatedlandfills and disposal areas near urban areas, in particular, arealready filled to capacity or approaching full capacity. Therefore, inorder to properly dispose of many items, new disposal sites must befound. In most cases, these new sites are either further away or lessdesirable than the existing sites. Accordingly, the cost of simply"throwing away" solid waste is increasing, both in terms of monetaryexpense (to find and ship to more remote locations) and the environment(committing an increasing amount of scarce physical resources to trash).

Although incineration is frequently useful as an alternative todisposing of solid waste items in a landfill or other disposal site,there is also increasing pressure from the environmentally conscious toreduce incineration as a means of disposal. Although incineration canreduce the bulk of materials shipped to disposal, there are other risks.First, incineration causes air pollution. Although sophisticated exhaustscrubbing systems exist to reduce this problem, these systems arefrequently expensive and inefficient.

Moreover, although soot, carbon monoxide, carbon dioxide, ozone, nitrousoxides, and sulfur compounds are the typical results of incineratingtrash (and the primary constituents of "smog"), these are only a few ofthe potential by-products of incinerating trash that includes man-madematerials, especially polymers. The incineration of such materials canresult in the release of potentially toxic materials, which arefrequently difficult to control.

Of course, recycling is one possible means of avoiding the problems withlandfills and incineration. Effective recycling procedures exist formany materials, including paper, aluminum, glass, and many plastics.However, man-made articles that are fabricated from more than onematerial are frequently difficult to recycle, as there can be recyclingincompatibilities between the materials. For example, a chemical that isuseful to dissolve and separate one type of plastic material may haveadverse effects on the properties of other materials that are bound tothe recycled plastic.

The foregoing difficulties have rendered it difficult to recycle usedcarpeting with any kind of efficiency. Carpeting frequently consists oftwo or more layers of backing material, a binding material (such as aglue), a reinforcing web, and a fibrous pile material. These materialsare frequently incompatible with each other in a recycling operation.For example, the means used to separate and reuse a layer of the backingmaterial might affect the usefulness of the pile material.Alternatively, a chemical used in the recycling process might dissolvetwo or more of the components, causing them to intermix and form a blendof the two materials having less desirable properties. The applicationof heat to melt certain materials can have the same effect.

Several attempts have been made to avoid the problems inherent inrecycling a complex man-made item comprising several materials, and tosuccessfully recycle carpet.

U.S. Pat. No. 5,230,473 to Hagguist et al. uses a combination ofchemical, heat, and mechanical means to strip and separate the variouscomponents from reclaimed carpet. However, the Hagguist system hasseveral disadvantages. It is a complex system that uses a variety ofmeans to separate the materials, and it attempts to separate the variouspile and substrate materials while leaving the backing largely intact.Therefore, the Hagguist system can be extremely expensive. Moreover, ituses potentially volatile and toxic chemicals, as well as pressurizedwater and steam. Finally, the scheme taught by Hagguist has not beenfound to be feasible or economically practicable, as it requires wastecarpet that is in substantially large and flat pieces, and does notproduce a level of contamination that is sufficiently low for efficientrecycling.

U.S. Pat. Nos. 5,497,949 and 5,518,188 to Sharer employ mechanical meansto decompose carpet into its constituent materials. However, theapparatus and method disclosed by the Sharer patents have been found tobe inefficient and result in unacceptable levels of contaminationbetween carpet fibers and backing material. Although this problem can bediminished by mixing reclaimed materials with a substantial amount ofnew or "virgin" material, this is inefficient and should be avoided.

In light of the various shortcomings of prior attempts to effectivelyrecycle spent carpeting, a need is recognized for a system and methodcapable of effectively and efficiently separating the constituentmaterials of used carpeting, so that those materials can be effectivelyrecycled into new product with a minimum of discarded material and aminimum need to add virgin material to reduce contamination levels.

A further need is recognized for a scheme that makes effective andefficient use of the reclaimed materials in new carpeting. The need forvirgin material should be kept to a minimum, in order to decrease costsand increase the amount of old material that is converted into newcarpeting.

SUMMARY OF THE INVENTION

The present system and method is capable of recycling carpet and similarheterogeneous materials at higher levels of efficiency and lower levelsof contamination than have previously been accomplished. To accomplishthis, the invention uses at least three separate mechanical grindingstages (including a coarse chopping operation) and at least threeseparate separation stages, configured in a unique and advantageousmanner.

The present invention is also capable of reusing much of the reclaimedmaterial in new products.

As discussed above, carpet materials typically have several layers ofdifferent materials. The simplest types of carpet might have fibrouspile material (nylon, for example) fused directly to a thermoplasticbacking. However, there can also be a secondary binder or substratelayer, a reinforcing web material through which the pile is attached, ora separate glue material that is used to anchor the pile to the backing.The present invention is operative to separate the lightweight fibrouspile from the remaining materials, so that the separate types ofmaterials can be recycled.

In recognition of the observation that the heavier backing materialsreclaimed from a carpet recycling operation are presently morerecyclable than are the lighter fibrous materials, the present inventionensures that as much as possible of the fibrous materials are removedfrom the backing materials, thereby reducing contamination andfacilitating reuse of the backing materials.

More specifically, the invention first chops used waste carpet intorelatively small pieces capable of being handled by an air conveyorsystem. The carpet materials are then ground into pieces small enough tofit through a 1/2 inch screen. At that time, the materials are separatedinto two categories: light materials are passed to a baling apparatus,and heavy materials continue through the separation process. The heavymaterials are then ground again, into pieces small enough to fit througha 1/8 inch screen. The materials are separated again, with the lightportion going to the baler, and the heavy materials continuing.

A vibratory screener is then used to separate the remaining materialsinto two further categories. The light materials are baled, and theheavy materials are again subjected to a separator. The fibers from thisstage are baled, and the remaining heavy materials are collected andreused.

At this stage, the heavy materials, comprising primarily the backingfrom the original waste carpet, can have a contamination level of lessthan two percent. Accordingly, the material is useful in a variety ofapplications, including the formation of new carpet.

In one embodiment of the invention, the reclaimed backing material isconveyed to a blender, at which time it can be blended in a specifiedratio with new or "virgin" material, if desired; melted; extruded from adie; and affixed as new backing to a carpet having new fibers, webbing,or other materials, and then used as desired.

Although the invention is primarily discussed herein as being directedto recycling used carpet materials, it should be noted that theinvention is also capable of decomposing and reclaiming materials fromother materials that are comprised of materials of different densities,such as plastic bottles and their labels, other plastic consumerarticles (such as telephones), and automotive interiors (such asdashboards and trunk liners).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the steps performed in theseparation stage of a carpet recycling system according to theinvention;

FIG. 2 is a schematic drawing of the separation stage of the carpetrecycling system set forth functionally in FIG. 1;

FIG. 3 is a block diagram illustrating the steps performed in thebacking material reuse stage of the carpet recycling system; and

FIG. 4 is a schematic drawing of the backing reuse stage of the carpetrecycling system set forth functionally in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described below, with reference to detailedillustrative embodiments. It will be apparent that the invention can beembodied in a wide variety of forms, some of which may be quitedifferent from those of the disclosed embodiments. Consequently, thespecific structural and functional details disclosed herein are merelyrepresentative and do not limit the scope of the invention.

A carpet recycling system according to the invention has two stages. Inthe first stage, the reclamation stage, used carpet pieces are processedand converted into reclaimed material. In the second stage, the reusestage, materials recovered in the reclamation stage are formed into newcarpet material.

Referring initially to FIG. 1, a block diagram is set forth whichfunctionally details the reclamation stage of a carpet recycling systemaccording to the invention. First, old carpet material in any size isreceived and chopped (step 110) into manageable pieces, typically from1/2 inch to several inches in size. These pieces are then agitated (step112) in a cyclone. This step serves at least three purposes. First, thecyclone regulates the feed rate of the chopped carpet pieces in thesystem. Second, the cyclone dissipates excess air in the conveyingstream. Third, the cyclone mechanically disturbs the carpet pieces,causing excess material and fibers to be dislodged from the backing. Allof the material is then passed to a first grinding or granulation step(step 114), at which time the carpet pieces are further ground into asmaller size. This step also serves to further dislodge carpet fibersfrom the backing.

The granulated material is then sent to a first separation step (step116), in which the dislodged fibers are again agitated (step 118) andbaled (step 120) for storage, eventual use, or to be discarded. Theremaining materials, namely everything except the dislodged fibersrecovered at step 116, are again agitated (step 122). The materials arethen passed to a second granulation step (step 124), at which time evensmaller pieces are made. These smaller pieces are separated in a secondseparation step (step 126); the fibers are again agitated (step 128) andbaled (step 130).

The materials remaining from the second separation step are thenscreened (step 132) on a vibratory screener. The light materials, orfibers, are agitated (step 134) and baled (step 136). The remainingpieces are again subjected to a third separation step (step 138). Theresulting fibers are agitated (step 140) and baled (step 142). Theremaining material is nearly all backing material; it is agitated (step144) and collected (step 146) for storage and reuse.

This procedure represents a unique combination of granulation,separation, and screening steps that has been found to result in therecovery of backing material with exceptionally low rates ofcontamination. This material can then be reused in new carpet backing orother products with the addition of little or no virgin material.

The reclamation stage of the invention set forth functionally above willnow be considered in conjunction with FIG. 2, which schematicallyillustrates the equipment that is used to perform the reclamation stage.

Waste carpet is received at a conveyor 210 and fed into a chopper 212.The chopper may take the form of a "knife hog," a shredder, or agrinder, and should be able to process the raw carpet material intopieces small enough to be handled by an air-driven conveyor system,e.g., from approximately 1/2 inch to several inches. In a preferredembodiment of the invention, the chopper 212 comprises a knife hog.

The chopped carpet pieces are then fed via a blower 214 into a cyclone216. The cyclone entrains the carpet pieces in a spiral airflow. Asdiscussed above, this accomplishes at least three purposes: it regulatesthe speed at which the carpet material is fed through the system,dissipates excess air, and it agitates the carpet pieces to physicallydislodge carpet fibers from the backing. In a preferred embodiment ofthe invention, the cyclone 216 used at this position is a #13 cyclone;such devices are available from a variety of sources. The cyclone has aside-mounted filter 218; this is used to trap any fibers from the airthat is normally discharged from the unit. Although the cyclone 216 isnot intended as a primary means of separating carpet fiber from thebacking, a small quantity of carpet fibers is normally found in thecyclone's airstream. The filter 218 prevents these fibers from beingdischarged into the environment.

From the cyclone 216, the carpet materials are dropped into a granulator220. The granulator grinds the carpet materials into smaller pieces. Ina preferred embodiment, the granulator 220 is a model X1400 granulatorfrom Cumberland Manufacturing Corp., and the unit is set to grind thematerials until they are able to fit through a 3/8 to 1/2 inch screen.The 1/2 inch screen size is presently preferred. As discussed above, notonly does the granulator 220 reduce the size of the carpet pieces beinghandled by the system, it tends to physically dislodge the carpet weband fiber material from the backing material.

The granulated pieces are then passed by a blower 222 to an elutriator224. An elutriator is a separating device that uses avertically-directed airstream to separate light materials from heavymaterials. In the present system, the carpet fibers are far lighter thanthe backing materials, and are captured by the airstream and directed toa first output. The heavier materials are not diverted by the airstream,and are directed to a second output. The lighter materials, namely thecarpet fibers, are conveyed by a blower 226 from the elutriator 224 to a#21 cyclone 228. This cyclone 228 again agitates the materials, in thiscase carpet fibers. The cyclone 228 also bears a side-mounted filter 230to prevent the undesired discharge of fibers. The cyclone 228 depositsits carpet fibers into an auger conveyor 232, at which time the fibersare conveyed into a baler 234.

The baler 234 receives, compresses, and bales carpet fibers reclaimed bythe system. The bales of fibers may then be stored, discarded, orincinerated; preferably, they are reused in a portion of the carpetrecycling operation.

The heavier materials in the elutriator 224 are dropped into a dualauger separator 236. The separator divides the stream of materials intotwo approximately equal streams, both of which are then processed inparallel by the system. One stream is handled by a first air conveyor238, and the other stream is handled by a second air conveyor 240. Thetwo streams of carpet materials are then drawn by blowers 242 and 244into two cyclones 246 and 248, which again regulate and agitate thecarpet materials. The cyclones 246 and 248 are fitted with filters 250and 252 to prevent the discharge of carpet fibers into the environment.At this step of the reclamation stage of the invention, the use of a #9cyclone is presently preferred.

The two cyclones 246 and 248 drop the carpet materials into twogranulators 254 and 256. These granulators 254 and 256, which in apreferred embodiment of the invention are model X1000 granulators fromCumberland Manufacturing Corp., grind the carpet materials until thepieces are smaller than a screen size, which can range from 1/8 inch to1/2 inch (preferably 1/8 inch). As discussed above, the stream ofmaterials is divided into two separate streams by the separator 236.Using two parallel #9 cyclones 246 and 248 and two granulators 254 and256 has been found to reduce the incidence of any "bottleneck" ofmaterial flow caused by the 1/8 inch screen size in the granulators,which is significantly smaller than the 1/2 inch screen in the previousgranulator 220. The two granulators 254 and 256 then send the materialsvia blowers 258 and 260 to a single elutriator 262. The elutriator 262separates the light materials (carpet fibers) from the heavy materials(backing and other materials). The light materials are passed via ablower 264 to the cyclone 228, and the fibers are eventually baled aspreviously discussed. The heavy materials are discharged into avibratory screener 266. The screener 266, which in a preferredembodiment is a device from Midwest Screen, Inc., also separates lightfibrous materials from heavy materials. The light materials (again,fibers) are collected in an air conveyor 268, and pulled via a blower270 into a cyclone 272. The cyclone 272, which is preferably a #19cyclone, bears a side-mounted filter 274, and discharges its materialsinto the conveyor 232, which feeds the baler 234.

The heavy materials from the screener 266 are received by an airconveyor 276 and passed via a blower 278 to an elutriator 280. Theelutriator 280 passes its carpet fibers through a blower 282 to thecyclone 272, and the fibers are baled. The heavy materials from theelutriator 280 now have extremely low levels of contamination fromcarpet fibers, as the fibers have been removed at four separate steps.The heavy materials, primarily carpet backing pieces, are passed via ablower 286 to a cyclone 288 (preferably a #10 cyclone), which removesthe last remaining trace of fibers via a filter 290, and drops thebacking pieces through a diverter valve 292 into a hopper 294.

The carpet backing pieces collected in the hopper 294 are suitable forfurther processing in accordance with the invention, as substantiallyall fibers have been removed and baled. The carpet backing can then beused by the reuse stage of the invention, which is set forthfunctionally in the block diagram of FIG. 3.

Reclaimed backing material 310, which in one embodiment of the inventionis received directly from the hopper 294, is first blended (step 314)with a quantity of virgin material 312 according to a specified"recipe." In one embodiment of the invention, the reclaimed material 310may be of sufficient quality and quantity that no virgin material 3 12is necessary. However, for varying qualities of reclaimed material 310and varying desired qualities for the finished product, differingamounts of virgin material 312 can be used in the invention. Moreover,coloring agents and other materials can be added at this step, ifdesired.

The blended material is then melted (step 316) and thoroughly mixed toform a homogeneous liquid. This hot liquid carpet backing material isthen extruded (step 318) in a shape suitable for use as new carpetbacking. While it is still hot, but after it has cooled sufficiently toretain its shape, the newly formed carpet backing material is combinedwith new fiber 322 material and embossed together (step 324) into newcarpet. In an alternative embodiment, the fiber 322 and newly formedcarpet backing material can be glued together with a separate adhesive;this can be accomplished after the backing material has cooled. The newcarpet is then rolled (step 326) and cut (step 328), if desired, intopieces of the desired size and shape.

The equipment used to perform the reuse stage of the invention is setforth schematically in FIG. 4. A blender 410 receives reclaimed backingmaterial in a first hopper 412 and virgin material in a second hopper414. Two types of blenders are suitable for use with the invention. Avolumetric blender is adjustable to feed material from hoppers atdifferent speeds. A gravimetric blender, which is preferred for thisapplication, allows material to be fed from the hoppers at a prescribedweight ratio; this is typically more precise. In a preferred embodimentof the invention, an X-series continuous gravimetric blender fromProcess Control Corp. is used as the blender 410.

The blender 410 feeds the specified ratio and quantity of materials intoan extruder 416. The extruder 416 includes a barrel with an internalauger that acts to feed the materials through the extruder while theyare being heated by heater bands mounted to the barrel. The auger mixesand advances the melted materials toward a die 418. The extruder 416forces the melted material through the die 418, which causes thematerial to assume a desired shape.

The new carpet web and fibers to be used with the new carpet are kept onrolls 420 and fed via an overhead conveyor 422 to a roll stand 424. Atthe roll stand 424, the extruded backing material is pressed against thenew web and fiber material to form new carpeting. In the disclosedembodiment of the invention, new carpet webbing and fibers are affixedto the melted material at the roll stand 424. In various alternativeembodiments of the invention, other fibrous materials, such as felt orfiberglass, can be affixed to the backing material for differentapplications.

The new carpeting is then cooled, gathered and rolled in an accumulator426, and cut as desired on a cutting press 428.

While various specific devices and subsystems have been disclosed abovefor use in an exemplary embodiment of the invention, it should be notedthat an apparatus and method according to the invention need not involvethose particular brands and types of equipment; other comparable devicescan be substituted.

Further, while the invention has been disclosed and described inrelation to a used carpet recycling operation, it should be observedthat the invention is equally applicable to recycling various othertypes of materials, such as plastic bottles, other plastic consumerarticles, automotive interiors (such as dashboards, trunk liners, andother similar parts), and other recyclable products that includematerials of different densities.

While certain exemplary structures and operations have been described,the invention is not so limited, and its scope is to be determinedaccording to the claims set forth below.

What is claimed is:
 1. A method for reclaiming backing material fromheavy-backed waste carpet material, comprising the steps of:chopping theheavy-backed waste carpet into pieces sufficiently small to be conveyedby a blower; grinding the waste carpet pieces into intermediate piecesto partially dislodge carpet fibers from the waste carpet material;separating the dislodged carpet fibers from the intermediate pieces;further grinding the intermediate pieces into final pieces to furtherdislodge carpet fibers; separating the dislodged carpet fibers from thefinal pieces of waste carpet material; screening the final pieces ofwaste carpet material into light material and heavy material; andcollecting the heavy material as reclaimed backing material.
 2. Themethod of claim 1, further comprising the step of passing the lightmaterial and the dislodged carpet fibers to a baler.
 3. A method forreclaiming a heavy material from a discarded, heavy-backed productcomprising a light material and the heavy material, comprising the stepsof:chopping the product into pieces sufficiently small to be conveyed bya blower; grinding the product into intermediate pieces to partiallydislodge the light material from the product; separating the dislodgedlight material from the intermediate pieces; further grinding theintermediate pieces into final pieces to further dislodge the lightmaterial; separating the dislodged light material from the final piecesof product; screening the final pieces of product into the lightmaterial and the heavy material; and collecting and reclaiming the heavymaterial.